Would a 155 ctx be too wide for size 9 boot? It looks to be less then 1cm wider for waist, tip and tail width.
154 CT is 25.1... 155 CTX is 26.1. 1 cm is a lot when you are talking about width. 1 cm is minute in terms of length.
26.1 is simply much too wide for a size 9 boot. You shouldn't go over 25.5 cm waist.